WO2010044257A1

WO2010044257A1 - Sputtering apparatus, method for forming thin film, and method for manufacturing field effect transistor

Info

Publication number: WO2010044257A1
Application number: PCT/JP2009/005342
Authority: WO
Inventors: 倉田敬臣; 清田淳也; 新井真; 赤松泰彦; 石橋暁; 斎藤一也
Original assignee: 株式会社アルバック
Priority date: 2008-10-16
Filing date: 2009-10-14
Publication date: 2010-04-22
Also published as: JP5309150B2; TWI428464B; KR20110042217A; US20110195562A1; JPWO2010044257A1; TW201024443A; CN102187010B; CN102187010A

Abstract

Disclosed is a sputtering apparatus which can reduce damage on a base layer. Also disclosed are a method for forming a thin film and a method for manufacturing a field effect transistor. An embodiment of the sputtering apparatus is a sputtering apparatus for forming a thin film on a surface to be processed of a substrate (10). The sputtering apparatus comprises a vacuum chamber (61), a supporting member (93), a target (80) and a magnet (83). The magnet (83) generates a plasma forming a to-be-sputtered region (80a) and moves the to-be-sputtered region (80a) between a first position where the to-be-sputtered region (80a) does not face the surface to be processed and a second position where the to-be-sputtered region (80a) faces the surface to be processed. Consequently, the incident energy of sputtering particles, which are incident upon the surface to be processed of the substrate (10) from the to-be-sputtered region (80a), is decreased, thereby enabling protection of a base layer.

Description

Sputtering apparatus, thin film forming method, and field effect transistor manufacturing method

The present invention relates to a sputtering apparatus for forming a thin film on a substrate, a thin film forming method using the apparatus, and a method for manufacturing a field effect transistor.

Conventionally, a sputtering apparatus has been used for forming a thin film on a substrate. The sputtering apparatus has a sputtering target (hereinafter referred to as “target”) disposed inside a vacuum chamber, and a plasma generating means for generating plasma near the surface of the target. A sputtering apparatus forms a thin film by sputtering the surface of a target with ions in plasma and depositing particles (sputtered particles) knocked out of the target on a substrate (see, for example, Patent Document 1).

JP 2007-39712 A

A thin film formed by a sputtering method (hereinafter also referred to as a “sputtered thin film”) has sputtered particles flying from a target incident on the surface of the substrate with high energy, so compared to a thin film formed by a vacuum deposition method or the like, High adhesion to the substrate. Therefore, the base layer (base film or base substrate) on which the sputtered thin film is formed is likely to be greatly damaged by collision with incident sputtered particles. For example, when an active layer of a thin film transistor is formed by a sputtering method, desired film characteristics may not be obtained due to damage to the underlayer.

In view of the circumstances as described above, an object of the present invention is to provide a sputtering apparatus, a thin film forming method, and a field effect transistor manufacturing method capable of reducing damage to an underlayer.

A sputtering apparatus according to one embodiment of the present invention is a sputtering apparatus that forms a thin film on a surface to be processed of a substrate, and includes a vacuum chamber, a support portion, a target, and plasma generation means.
The vacuum chamber maintains a vacuum state.
The support portion is disposed inside the vacuum chamber and supports the substrate.
The target is disposed in parallel to the surface to be processed of the substrate supported by the support portion, and has a surface to be sputtered.
The plasma generating means generates a plasma that forms a region to be sputtered from which sputtered particles are emitted by sputtering the surface to be sputtered, a first position where the region to be sputtered does not face the surface to be processed, and The sputtered region is moved between the sputtered region and the second position facing the processing surface.

In a thin film forming method according to one embodiment of the present invention, a substrate having a surface to be processed is placed in a vacuum chamber.
A plasma for sputtering the target is generated.
The sputtered region of the target is moved between a first position where the sputtered region does not face the treated surface and a second position where the sputtered region faces the treated surface.

In a method for manufacturing a field effect transistor according to one embodiment of the present invention, a gate insulating film is formed over a substrate.
The substrate is placed inside a vacuum chamber in which a target having an In—Ga—Zn—O-based composition is placed.
Plasma for sputtering the target is generated.
The sputtered region of the target is moved between a first position where the sputtered region does not face the surface to be treated and a second position where the sputtered region faces the surface to be treated, An active layer is formed on the gate insulating film.

It is a top view which shows the vacuum processing apparatus which concerns on 1st Embodiment. It is a top view which shows a holding mechanism. It is a top view which shows a 1st sputtering chamber. It is a schematic diagram which shows the mode of a sputter | spatter. It is a flowchart which shows a substrate processing process. It is a figure which shows the sputtering device used for experiment. It is a figure which shows the film thickness distribution of the thin film obtained by experiment. It is a figure explaining each incidence of sputtered particles. It is a figure which shows the film-forming rate of the thin film obtained by experiment It is a figure which shows the on-current characteristic and off-current characteristic when each sample of the thin-film transistor manufactured by experiment is annealed at 200 degreeC. It is a figure which shows the on-current characteristic and off-current characteristic when each sample of the thin-film transistor manufactured by experiment is annealed at 400 degreeC. It is a top view which shows the 1st sputtering chamber which concerns on 2nd Embodiment.

A sputtering apparatus according to an embodiment of the present invention is a sputtering apparatus that forms a thin film on a surface to be processed of a substrate, and includes a vacuum chamber, a support unit, a target, and plasma generation means.
The vacuum chamber maintains a vacuum state.
The support portion is disposed inside the vacuum chamber and supports the substrate.
The target is disposed in parallel to the surface to be processed of the substrate supported by the support portion and has a surface to be sputtered.
The plasma generating means generates a plasma for forming a sputtered region from which sputtered particles are emitted by sputtering the sputtered surface, a first position where the sputtered region does not face the treated surface, The sputtered region is moved between the sputtered region and the second position facing the processing surface.

The sputtering apparatus changes the incident angle of the sputtered particles with respect to the processing surface of the substrate by moving the sputtered region. Since the sputtered particles incident in the oblique direction with respect to the surface to be processed from the first position have lower incident energy (number of incident particles per unit area) than those incident in the vertical direction, the damage given to the underlying layer is small. After that, by causing the sputtered particles to enter from the second position in the vertical direction, it is possible to achieve film formation with little damage to the underlayer and high film formation speed.

The plasma generating means may include a magnet for forming a magnetic field on the surface to be sputtered of the target, and the magnet may be arranged to be movable relative to the support portion.

The plasma generating means controls the plasma density by a magnetic field applied by a magnet (magnetron sputtering). In magnetron sputtering, the sputtered region (sputtered region) is unevenly distributed on the surface of the target. By moving the magnet, the region to be sputtered can be moved, and the incident direction of the sputtered particles with respect to the surface to be processed can be controlled.

The sputter surface has a first region that does not face the surface to be treated and a second region that faces the surface to be treated, and the magnet includes the first region and the second region. It may be arranged so as to be movable between the two.

If the first region on the surface to be sputtered, that is, the region located obliquely from the surface to be processed is the sputter region, the incident direction of the sputtered particles with respect to the surface to be processed can be made oblique. Further, if the second region, that is, the region positioned in the vertical direction from the surface to be processed is the sputtered region, the incident direction can be set to the vertical direction.

The target may move with the magnet.

¡By moving the target together with the magnet, it is possible to control the direction of the sputtered region as viewed from the surface to be treated.

In a thin film forming method according to an embodiment of the present invention, a substrate having a surface to be processed is placed in a vacuum chamber.
A plasma for sputtering the target is generated.
The sputtered region of the target is moved between a first position where the sputtered region does not face the treated surface and a second position where the sputtered region faces the treated surface.

A method of manufacturing a field effect transistor according to an embodiment of the present invention includes: forming a gate insulating film on a substrate; and placing the substrate inside a vacuum chamber in which a target having an In—Ga—Zn—O-based composition is disposed. To place.
Plasma for sputtering the target is generated.
The sputtered region of the target is moved between a first position where the sputtered region does not face the surface to be treated and a second position where the sputtered region faces the surface to be treated, An active layer is formed on the gate insulating film.

According to this method of manufacturing a field effect transistor, it is possible to protect the gate insulating film that is easily damaged by the incident energy when the active layer is formed by sputtering.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
A vacuum processing apparatus 100 according to the first embodiment will be described.
FIG. 1 is a schematic plan view showing a vacuum processing apparatus 100.

The vacuum processing apparatus 100 is an apparatus for processing, for example, a glass substrate (hereinafter simply referred to as a substrate) 10 used for a display as a base material, and is typically a field effect transistor having a so-called bottom gate type transistor structure. It is a device that bears a part of the manufacturing.

The vacuum processing apparatus 100 includes a cluster type processing unit 50, an inline type processing unit 60, and an attitude conversion chamber 70. Each of these chambers is formed inside a single vacuum chamber or a combination of a plurality of vacuum chambers.

The cluster processing unit 50 includes a plurality of horizontal processing chambers for processing the substrate 10 in a state where the substrate 10 is substantially horizontal. Typically, the cluster processing unit 50 includes a load lock chamber 51, a transfer chamber 53, and a plurality of CVD (Chemical Vapor Deposition) chambers 52.

The load lock chamber 51 switches the atmospheric pressure and the vacuum state, loads the substrate 10 from the outside of the vacuum processing apparatus 100, and unloads the substrate 10 to the outside. The transfer chamber 53 includes a transfer robot (not shown). Each CVD chamber 52 is connected to the transfer chamber 53 and performs a CVD process on the substrate 10. The transfer robot in the transfer chamber 53 carries the substrate 10 into the load lock chamber 51, each CVD chamber 52, and the posture changing chamber 70 described later, and also carries the substrate 10 out of each chamber.

In the CVD chamber 52, a gate insulating film of a field effect transistor is typically formed.

The inside of the transfer chamber 53 and the CVD chamber 52 can be maintained at a predetermined degree of vacuum.

The posture conversion chamber 70 converts the posture of the substrate 10 from horizontal to vertical and from vertical to horizontal. For example, as shown in FIG. 2, a holding mechanism 71 that holds the substrate 10 is provided in the posture change chamber 70, and the holding mechanism 71 is configured to be rotatable about a rotation shaft 72. The holding mechanism 71 holds the substrate 10 by a mechanical chuck or a vacuum chuck. The posture changing chamber 70 can be maintained at substantially the same degree of vacuum as the transfer chamber 53.

The holding mechanism 71 may be rotated by driving a driving mechanism (not shown) connected to both ends of the holding mechanism 71.

The cluster processing unit 50 may be provided with a heating chamber and a chamber for performing other processes in addition to the CVD chamber 52 and the posture changing chamber 70 connected to the transfer chamber 53.

The in-line type processing unit 60 includes a first sputtering chamber 61 (vacuum chamber), a second sputtering chamber 62, and a buffer chamber 63, and processes the substrate 10 in a state where the substrate 10 is set substantially vertically.

In the first sputtering chamber 61, a thin film (hereinafter simply referred to as an IGZO film) having an In—Ga—Zn—O-based composition is typically formed on the substrate 10 as will be described later. In the second sputtering chamber 62, a stopper layer film is formed on the IGZO film. The IGZO film constitutes an active layer of the field effect transistor. The stopper layer film functions as an etching protective layer that protects the channel region of the IGZO film from the etchant in the patterning step of the metal film constituting the source electrode and the drain electrode and the step of etching away the unnecessary region of the IGZO film.

The first sputtering chamber 61 has a sputtering cathode Tc containing a target material for forming the IGZO film. The second sputtering chamber 62 has a single sputtering cathode Ts containing a target material for forming a stopper layer film.

As described later, the first sputtering chamber 61 is configured as a fixed film forming type sputtering apparatus. On the other hand, the second sputtering chamber 62 may be configured as a fixed film forming type sputtering apparatus or may be configured as a through film forming type sputtering apparatus.

In the first sputtering chamber 61, the second sputtering chamber 62, and the buffer chamber 63, for example, a two-path transport path for the substrate 10 constituted by an outward path 64 and a return path 65 is prepared, and the substrate 10 is in a vertical state. Alternatively, a support mechanism (not shown) that supports the device in a state slightly tilted from the vertical is provided. The substrate 10 supported by the support mechanism is transported by a mechanism such as a transport roller and a rack and pinion (not shown).

A gate valve 54 is provided between the chambers, and these gate valves 54 are individually controlled to open and close.

The buffer chamber 63 is connected between the posture changing chamber 70 and the second sputter chamber 62 and functions to be a buffer region for the pressure atmosphere of each of the posture changing chamber 70 and the second sputter chamber 62. For example, when the gate valve 54 provided between the posture changing chamber 70 and the buffer chamber 63 is opened, the buffer chamber 63 is vacuumed so that the pressure is substantially the same as the pressure in the posture changing chamber 70. The degree is controlled. Further, when the gate valve 54 provided between the buffer chamber 63 and the second sputtering chamber 62 is opened, the buffer is set so that the pressure is substantially the same as the pressure in the second sputtering chamber 62. The degree of vacuum in the chamber 63 is controlled.

In the CVD chamber 52, a special gas such as a cleaning gas may be used to clean the chamber. For example, when the CVD chamber 52 is configured by a vertical apparatus, a support mechanism and a transport mechanism unique to the vertical processing apparatus, such as those provided in the second sputtering chamber 62 described above, are made of a special gas. There are concerns about problems such as corrosion. However, in the present embodiment, since the CVD chamber 52 is composed of a horizontal apparatus, such a problem can be solved.

On the other hand, when the sputtering apparatus is configured as a horizontal apparatus, for example, when the target is disposed immediately above the substrate, the target material attached to the periphery of the target may fall on the substrate and contaminate the substrate 10. . On the other hand, when the target is disposed under the substrate, the target material attached to the deposition preventing plate disposed around the substrate may fall on the electrode and contaminate the electrode. There is concern about abnormal discharge occurring during the sputtering process due to these contaminations. However, these problems can be solved by configuring the second sputtering chamber 62 as a vertical processing chamber.

Next, details of the first sputtering chamber 61 will be described. FIG. 3 is a schematic plan view showing the first sputtering chamber 61.

As described above, the first sputtering chamber 61 has the sputtering cathode Tc. The sputter cathode Tc includes a target 80, a backing plate 82, and a magnet 83. The first sputtering chamber 61 is connected to a gas introduction line (not shown), and a sputtering gas such as argon and a reactive gas such as oxygen are introduced into the first sputtering chamber 61 through the gas introduction line. The

The target 80 is composed of an ingot or a sintered body of a film forming material. In this embodiment mode, an alloy ingot or a sintered body material having an In—Ga—Zn—O composition is used. The target 80 is attached so that the surface to be sputtered is parallel to the surface to be processed of the substrate 10. The target 80 has a larger area than the substrate 10. The surface to be sputtered of the target 80 has a region facing the substrate 10 (second region) and a region not facing the first region (first region). Of the surface to be sputtered of the target 80, a region where sputtering proceeds (described later) is a sputtered region 80a.

The backing plate 82 is configured as an AC power source (including a high frequency power source) (not shown) or an electrode connected to a DC power source. The backing plate 82 may include a cooling mechanism in which a cooling medium such as cooling water circulates. The backing plate 82 is attached to the back surface of the target 80 (the surface opposite to the surface to be sputtered).

The magnet 83 is composed of a combination of a permanent magnet and a yoke, and forms a predetermined magnetic field 84 near the surface of the target 80 (surface to be sputtered). The magnet 83 is attached to the back side of the backing plate 82 (on the side opposite to the target 80), and is parallel to the surface to be sputtered of the target 80 (at the same time parallel to the surface to be processed of the substrate 10) by a driving mechanism (not shown). It is configured to be movable.

The sputter cathode Tc configured as described above generates plasma in the first sputter chamber 61 by plasma generating means including the power source, the backing plate 82, the magnet 83, the gas introduction line, and the like. That is, when a predetermined AC power source or DC power source is applied to the backing plate 82, sputtering gas plasma is formed in the vicinity of the surface to be sputtered of the target 80. Then, the sputtering target surface of the target 80 is sputtered by ions in the plasma (a sputtering target region 80a is formed). Further, a high-density plasma (magnetron discharge) is generated by the magnetic field formed on the target surface by the magnet 83, and it becomes possible to obtain a plasma density distribution corresponding to the magnetic field distribution. By controlling the plasma density, the entire region of the surface to be sputtered is not sputtered uniformly, and the region that becomes the sputtered region 80a is limited. The sputtered region 80 a depends on the location of the magnet 83 and moves as the magnet 83 moves.

As shown in FIG. 3, the sputtered particles generated from the sputtered region 80a are emitted from the sputtered region 80a over the angular range S. The angle range S is controlled by plasma forming conditions and the like. The sputtered particles include particles that protrude in the vertical direction from the sputtered region 80 a and particles that protrude in an oblique direction from the surface of the target 80. The sputtered particles that have jumped out of the target 80 are deposited on the surface to be processed of the substrate 10 to form a thin film.

The substrate 10 is disposed in the first sputtering chamber 61. The substrate 10 is supported by a support portion 93 including a support plate 91 and a clamp mechanism 92, and is stationary (fixed) at a predetermined position on the return path 65 during film formation. The clamp mechanism 92 holds the peripheral portion of the substrate 10 supported by the support region of the support plate 91 facing the sputter cathode Tc.

The arrangement relationship between the magnet 83 and the substrate 10 will be described.
At the start of sputtering, the magnet 83 is disposed at the first position. The first position corresponds to a position where the magnet 83 does not face the substrate 10 through the target 80, that is, the back surface of a region of the surface to be sputtered of the target 80 that does not face the substrate 10. As will be described later, when the sputtering proceeds, the magnet 83 is driven by the drive mechanism and moves to a second position that is a position facing the substrate 10.

The processing sequence of the substrate 10 in the vacuum processing apparatus 100 configured as described above will be described. FIG. 5 is a flowchart showing the order.

The transfer chamber 53, the CVD chamber 52, the posture changing chamber 70, the buffer chamber 63, the first sputter chamber 61, and the second sputter chamber 62 are each maintained in a predetermined vacuum state. First, the substrate 10 is loaded into the load lock chamber 51 (step 101). Thereafter, the substrate 10 is carried into the CVD chamber 52 through the transfer chamber 53, and a predetermined film, for example, a gate insulating film is formed on the substrate 10 by the CVD process (step 102). After the CVD process, the substrate 10 is carried into the posture changing chamber 70 through the transfer chamber 53, and the posture of the substrate 10 is changed from the horizontal posture to the vertical posture (step 103).

The substrate 10 in a vertical posture is carried into the sputtering chamber through the buffer chamber 63 and is transferred to the end of the first sputtering chamber 61 through the forward path 64. Thereafter, the substrate 10 passes through the return path 65, is stopped in the first sputtering chamber 61, and is subjected to the sputtering process as follows. Thereby, for example, an IGZO film is formed on the surface of the substrate 10 (step 104).

Referring to FIG. 3, the substrate 10 is transported through the first sputtering chamber 61 by the support mechanism and stopped at a position facing the sputtering cathode Tc. A predetermined flow rate of sputtering gas (such as argon gas and oxygen gas) is introduced into the first sputtering chamber 61. As described above, an electric field and a magnetic field are applied to the sputtering gas, and sputtering is started.

FIG. 4 is a diagram showing a state of sputtering.
Sputtering proceeds in the order of FIGS. 4 (A), (B), and (C). At the start stage of sputtering shown in FIG. 4A, the magnet 83 is disposed at a first position that does not face the substrate 10. The sputtered region 80 a is generated in the vicinity of the magnet 83 on the sputtered surface of the target 80. The sputtered particles emitted from the region to be sputtered 80a are diffused at a certain angle and reach the surface to be processed of the substrate 10 to be deposited. The sputtered particles that reach the surface to be processed at this stage are sputtered particles emitted from the sputtered region 80a in an oblique direction with respect to the sputtered surface. Since the region to be sputtered 80a does not face the substrate 10, the sputtered particles emitted in the direction perpendicular to the surface to be sputtered do not reach the surface to be treated.

When film formation is performed with sputtered particles incident obliquely on a part of the surface to be processed of the substrate 10 that is close to the sputtered region 80a, the magnet 83 is driven by the driving mechanism, and the state shown in FIG. Move as shown. This movement causes the magnet 83 to move from a first position that does not face the substrate 10 to a second position that faces the substrate 10. Even during this movement, sputtering proceeds (an electric field and a magnetic field are applied). The sputtered region 80 a also moves on the sputtered surface together with the magnet 83 and takes a position facing the substrate 10. As a result, among the sputtered particles emitted from the sputtered region 80a, sputtered particles emitted in an oblique direction and a vertical direction with respect to the sputtered surface reach the processing surface of the substrate 10. A part of the sputtered particles emitted in the oblique direction reaches a (novel) region where the film is not formed on the surface to be processed. On the other hand, the sputtered particles emitted in the vertical direction reach the region where the film has already been formed in the previous stage shown in FIG.

When a film having a predetermined film thickness is formed by the sputtered particles emitted in the vertical direction, the magnet 83 is further moved as shown in FIG. 4B, and emitted in an oblique direction at the stage shown in FIG. 4B. The region formed by the sputtered particles is further formed by the sputtered particles emitted in the vertical direction. Thereafter, the magnet 83 moves in the same manner, and film formation proceeds over the entire region of the surface to be processed of the substrate 10. Although the movement of the magnet 83 is continuous, it may be stepwise (repeating progress and pause).

As described above, the surface to be processed of the substrate 10 is first formed by the sputtered particles emitted in the oblique direction from the sputtered region 80a, and then formed by the sputtered particles emitted in the vertical direction. The The number of sputtered particles emitted in an oblique direction reaches a unit area of the surface to be processed is smaller than that in the vertical direction. Thereby, the incident energy per unit area received by the surface to be processed is also reduced, and the damage received by the surface to be processed is small. On the other hand, since the number of sputtered particles in the oblique direction is small, the film forming speed is slow. However, the subsequent vertical sputtered particles can be formed without significantly reducing the overall film forming speed. Since the sputtered particles in the vertical direction reach only the region where the surface to be processed is already formed, the existing film serves as a buffer material and does not damage the surface to be processed.

In the sputtering process according to the present embodiment, when the magnet 83 moves, film formation proceeds by the above process in any region of the surface to be processed of the substrate 10, reducing the damage received on the surface to be processed, and It is possible to keep the deposition rate high.

The substrate 10 on which the IGZO film is formed in the first sputtering chamber 61 is transferred to the second sputtering chamber 62 together with the support plate 91. In the second sputtering chamber 62, a stopper layer made of, for example, a silicon oxide film is formed on the surface of the substrate 10 (step 104).

The film formation process in the second sputter chamber 62 employs a fixed film formation method in which the substrate 10 is made to stand still in the second sputter chamber 62 in the same manner as the film formation process in the first sputter chamber 61. . However, the present invention is not limited to this, and a passing film formation method in which the substrate 10 is formed in the process of passing through the second sputtering chamber 62 may be employed.

After the sputtering process, the substrate 10 is carried into the posture changing chamber 70 through the buffer chamber 63, and the posture of the substrate 10 is changed from the vertical posture to the horizontal posture (step 105). Thereafter, the substrate 10 is unloaded outside the vacuum processing apparatus 100 via the transfer chamber 53 and the load lock chamber 51 (step 106).

As described above, according to the present embodiment, CVD film formation and sputter film formation can be performed consistently within one vacuum processing apparatus 100 without exposing the substrate 10 to the atmosphere. Thereby, productivity can be improved. Further, since moisture and dust in the atmosphere can be prevented from adhering to the substrate 10, it is possible to improve the film quality.

In addition, as described above, by forming the initial IGZO film with low incident energy, damage to the gate insulating film, which is the base layer, can be reduced, so that a field effect thin film transistor with high characteristics can be manufactured. it can.

(Second Embodiment)
A vacuum processing apparatus according to the second embodiment will be described.
In the following description, description of parts having the same configuration as that of the above-described embodiment will be simplified.
FIG. 12 is a schematic plan view showing the first sputtering chamber 261 according to the second embodiment.

Unlike the vacuum processing apparatus 100 according to the first embodiment, the vacuum processing apparatus according to this embodiment includes a target plate 281 that moves together with the magnet 283.

The first sputtering chamber 261 of the vacuum processing apparatus has a sputtering cathode Td. The sputter cathode Td is configured to be movable with respect to the substrate 210 that is the film formation target, and in particular, configured so that the target plate 281 can take a position that does not face the substrate 210.
The sputter cathode Td includes a target plate 281, a backing plate 282, and a magnet 283.

The sputter cathode Td according to the present embodiment is configured to be movable with respect to the substrate 210 that is a film formation target.
The target plate 281 is attached so as to be parallel to the surface to be processed of the substrate 210. The target plate 281 faces the substrate 210 or does not face the substrate 210 by the movement of the sputtering cathode Td. Therefore, the size of the target plate 281 is smaller than the size of the substrate 210. Of the surface to be sputtered of the target plate 281, a region where sputtering proceeds (described later) is defined as a sputtered region 280 a.

The backing plate 282 is attached to the back surface (surface opposite to the surface to be sputtered) of the target plate 281.
The magnet 283 is disposed on the back side of the backing plate 282 (the side opposite to the target 280). Unlike the magnet 83 according to the first embodiment, the magnet 283 does not move with respect to the target plate 281 and the backing plate 282, and may be fixed thereto. Note that the magnet 283 may not be fixed to the backing plate 282, and the magnet 283 may be moved by a drive source different from the backing plate 282.

The sputter cathode Td is moved in a direction parallel to the surface to be sputtered of the target plate 281 with respect to the substrate 210 by a driving mechanism (not shown). The sputter cathode Td takes a first position where the target plate 281 does not face the substrate 210 and a second position where the target plate 281 faces the substrate 210.

Sputtering by the vacuum processing apparatus configured as described above will be described.
Similar to the sputtering according to the first embodiment, the sputtering gas is turned into plasma by the applied electric and magnetic fields. The sputtered region 280a on the target plate 281 does not move on the target plate 281 and is relatively fixed. Note that the size, shape, and the like of the region to be sputtered can be changed depending on sputtering conditions such as magnetic field strength.

At the start of sputtering, the sputtering cathode Td exists at a position where the target plate 281 does not face the substrate 210. Therefore, among the sputtered particles emitted from the sputtered region 280a of the target plate 281, only those emitted in the oblique direction with respect to the sputtered surface reach the treated surface of the substrate 210 and are emitted in the vertical direction. Things do not reach the surface to be processed. The sputter cathode Td moves while the target plate 281 is sputtered.

As a result, in the surface to be processed, the region formed by the sputtered particles incident in the oblique direction is further formed by the sputtered particles incident in the vertical direction, and the region not formed by the sputtered particles is inclined. The film is formed by sputtered particles incident in the direction. The sputter cathode Td moves continuously or intermittently, and the entire region of the surface to be processed of the substrate 210 is formed with sputtered particles.

As described above, film formation with little damage to the surface to be processed and high film formation speed is achieved.

Hereinafter, the difference in the film formation rate and the damage to the underlying layer between the sputtered particles emitted obliquely with respect to the target sputtering surface and the sputtered particles emitted in the vertical direction will be described.

FIG. 6 is a schematic configuration diagram of a sputtering apparatus for explaining an experiment conducted by the present inventors. This sputtering apparatus includes two sputtering cathodes T1 and T2, each having a target 11, a backing plate 12, and a magnet 13. The backing plates 12 of the sputter cathodes T1 and T2 are connected to the electrodes of the AC power source 14, respectively. As the target 11, a target material having an In—Ga—Zn—O composition was used.

A substrate having a silicon oxide film formed as a gate insulating film on the surface was disposed opposite to the sputter cathodes T1 and T2. The distance (TS distance) between the sputter cathode and the substrate was 260 mm. The center of the substrate was aligned with the intermediate point (point A) between the sputter cathodes T1 and T2. The distance from this point A to the center (point B) of each target 11 is 100 mm. Formed by introducing a predetermined flow rate of oxygen gas into a vacuum chamber maintained in a reduced pressure argon atmosphere (flow rate 230 sccm, partial pressure 0.74 Pa) and applying AC power (0.6 kW) between the sputter cathodes T1 and T2. Each target 11 was sputtered with the generated plasma 15.

FIG. 7 shows the measurement results of the film thickness at each position on the substrate with point A as the origin. The film thickness at each point was a relative ratio converted with the film thickness at the point A as 1. The substrate temperature was room temperature. The point C was a position 250 mm away from the point A, and the distance from the outer peripheral side of the magnet 13 of the sputter cathode T2 was 82.5 mm. In the figure, “◇” indicates the film thickness when the oxygen introduction amount is 1 sccm (partial pressure 0.004 Pa), “■” indicates the film thickness when the oxygen introduction amount is 5 sccm (partial pressure 0.02 Pa), and “Δ” indicates The film thickness when the oxygen introduction amount is 25 sccm (partial pressure 0.08 Pa), and “●” indicates the film thickness when the oxygen introduction amount is 50 sccm (partial pressure 0.14 Pa).

As shown in FIG. 7, the film thickness at point A where the sputtered particles emitted from the two sputter cathodes T1 and T2 reach is the largest, and the film thickness decreases as the distance from the point A increases. The point C is a deposition region of sputtered particles emitted obliquely from the sputter cathode T2, and thus has a smaller film thickness than the sputtered particle deposition region (point B) incident from the sputter cathode T2 in the vertical direction. The incident angle θ of the sputtered particles at this point C was 72.39 ° as shown in FIG.

FIG. 9 is a diagram showing the relationship between the introduced partial pressure and the film formation rate measured at points A, B and C. It was confirmed that the film formation rate decreased as the oxygen partial pressure (oxygen introduction amount) increased regardless of the film formation position.

At each of points A and C, thin film transistors each having an active layer made of an IGZO film formed with different oxygen partial pressures were produced. The active layer was annealed by heating each transistor sample in air at 200 ° C. for 15 minutes. And the on-current characteristic and the off-current characteristic were measured about each sample. The result is shown in FIG. In the figure, the vertical axis represents on-current or off-current, and the horizontal axis represents oxygen partial pressure during the formation of the IGZO film. For reference, the transistor characteristics of a sample in which an IGZO film is formed by a pass film formation method by RF sputtering are also shown. In the figure, “△” is the off current at point C, “▲” is the on current at point C, “◇” is the off current at point A, “◆” is the on current at point A, and “◯” is the reference sample. The off current, “●”, is the on current of the reference sample.

As is clear from the results in FIG. 10, the on-current decreases as the oxygen partial pressure increases in each sample. This is presumably because the conductive properties of the active layer are lowered by the increase in the oxygen concentration in the film. Further, when the samples at point A and point C are compared, the sample at point A has a lower on-current than point C. This is thought to be due to the fact that the underlying film (gate insulating film) suffered significant damage due to collision with sputtered particles during the formation of the active layer (IGZO film), and the desired film quality of the underlying film could not be maintained. It is done. In addition, the sample at the point C had the same on-current characteristics as the reference sample.

On the other hand, FIG. 11 shows experimental results obtained by measuring the on-current characteristics and off-current characteristics of the thin film transistor when the annealing conditions of the active layer are 400 ° C. for 15 minutes in the atmosphere. Under this annealing condition, there was no difference in on-current characteristics for each sample. However, regarding the off-current characteristics, it was confirmed that the sample at point A was higher than the sample at point C and each sample for reference. This is presumably because the base film was greatly damaged by collision with the sputtered particles during the formation of the active layer, and the desired insulating properties were lost.

It was also confirmed that high on-current characteristics can be obtained without being affected by oxygen partial pressure by increasing the annealing temperature.

As is apparent from the above results, when the active layer of the thin film transistor is formed by sputtering, the on-current is high and the off-current is low by forming the initial layer of the thin film with sputtered particles incident on the substrate from an oblique direction. Excellent transistor characteristics can be obtained. In addition, an active layer having an In—Ga—Zn—O-based composition having desired transistor characteristics can be stably manufactured.

The embodiment of the present invention has been described above. Of course, the present invention is not limited to this, and various modifications can be made based on the technical idea of the present invention.

In the above-described embodiment, the method for manufacturing a thin film transistor using an IGZO film as an active layer has been described as an example. However, the present invention can also be applied to the case where another film forming material such as a metal material is formed by sputtering. is there.

DESCRIPTION OF SYMBOLS 10 Substrate 11 Target 13 Magnet 61 First sputter chamber 71 Holding mechanism 80 Target 83 Magnet 93 Support part 100 Vacuum processing apparatus 210 Substrate 261 First sputter chamber 280 Target 283 Magnet

Claims

A sputtering apparatus for forming a thin film on a surface to be processed of a substrate,
A vacuum chamber capable of maintaining a vacuum state;
A support part disposed inside the vacuum chamber and supporting the substrate;
A target that is arranged in parallel to the surface to be processed of the substrate supported by the support and has a surface to be sputtered;
Sputtering the surface to be sputtered generates plasma to form a region to be sputtered from which sputtered particles are emitted, and the region to be sputtered is not opposed to the surface to be processed, and the region to be sputtered is the surface to be sputtered. And a plasma generating means for moving the region to be sputtered between a second position facing the processing surface.
The sputtering apparatus according to claim 1,
The plasma generating means includes a magnet for forming a magnetic field on the surface to be sputtered of the target,
The said magnet is arrange | positioned so that relative movement with respect to the said support part is possible freely. Sputtering apparatus.
The sputtering apparatus according to claim 2,
The sputter surface has a first region that does not face the surface to be treated and a second region that faces the surface to be treated.
The said magnet is arrange | positioned movably between the said 1st area | region and the said 2nd area | region. Sputtering apparatus.
The sputtering apparatus according to claim 2,
The target moves together with the magnet. Sputtering apparatus.
A substrate having a surface to be processed is placed in a vacuum chamber,
Generate plasma to sputter the target,
Thin film formation is performed by moving the sputtering area of the target between a first position where the sputtering area does not face the surface to be processed and a second position where the sputtering area faces the surface to be processed. Method.
A gate insulating film is formed on the substrate,
The substrate is placed inside a vacuum chamber in which a target having an In—Ga—Zn—O-based composition is placed,
Generating plasma to sputter the target;
Moving the sputtered region of the target between a first position where the sputtered region does not face the treated surface and a second position where the sputtered region faces the treated surface; A method of manufacturing a field effect transistor, wherein an active layer is formed on a gate insulating film.